The present invention relates generally to lifting tools for wind turbines and more particularly to manual lifting tools.
Wind turbines are devices that convert mechanical energy to electrical energy. A typical wind turbine includes a nacelle mounted on a tower housing a drive train for transmitting the rotation of a wind rotor to an electric generator and other components such as a yaw drive which rotates the wind turbine, several controllers and a brake. The wind rotor comprises a rotor hub supporting a number of blades extending radially therefore capturing the kinetic energy of the wind and causing the drive-train rotational motion.
Wind turbines are designed to ensure that their main components have a long working life, which means that regular maintenance work on the parts subject to greatest wear shall be carried out. Some of these components, particularly the generator, the gearbox, the rotor and the transformer, are extremely heavy and therefore require the use of a crane for handling.
Bearing in mind the strict limitations regarding maintenance work, given that wind turbines are installed in tall towers and built in, generally, in solitary areas, the use of external cranes leads to problems of availability and cost.
To face these problems wind turbines can be provided with internal cranes to carry out maintenance work on their heavier components without the need for external resources.
For example U.S. Pat. No. 7,748,547 in the name of the applicant discloses a movable independent crane system that can be used temporarily for mounting, moving or replacing components of wind turbines.
When a maintenance work shall be carried out when the wind turbine is de-energized or in commissioning mode, internal cranes needing an electric supply cannot be used so that there is a need of lifting tools that can operate in these situations for performing a variety of maintenance works.